Gulf of Maine Seasonal Sea Surface Temperature Update

Seasonal Patterns in Sea Surface Temperatures

Author

Adam Kemberling

Published

September 27, 2022

About the Updates:

Over the past decade, scientists at the Gulf of Maine Research Institute have led a body of research that highlights the rapid pace of warming in the Gulf of Maine. To keep you informed, we share seasonal updates about conditions in the Gulf of Maine.

Note About the Data: The figures in this report are created using remotely-sensed satellite data as part of publicly funded research efforts. Satellite SST data was obtained from NOAA’s National Center for Environmental Information (NCEI), with all maps and figures displaying NOAA’s Optimum Interpolation Sea Surface Temperature Data.

Note on Preliminary Data: This dataset has a 2-week latency period, during which values may change due to quality control measures. Any data within 14 days of the publishing date may be subject to change.

The Gulf of Maine Region

For analyses like these, it is important to be clear about the spatial extent that “defines” the Gulf of Maine (Figure 1), as different borders could produce different results. The spatial domain we use as the “Gulf of Maine” is displayed below. This area is consistent with previous reports and publications GMRI has produced.

A overhead view of the Gulf of Maine region. Landmasses and political boundaries for the United States and Canada are displayed. A blue dotted line outlining a box with a transparent blue fill is shown to demark where satellite data for the analysis has been used.

For this seasonal report, we present an analysis of SST for Summer (June 1st - August 31st).

Highlights

The average SST for the Gulf of Maine during the summer (June 1st - August 31st) of 2022 was 62.14°F, making it the 3rd hottest summer on record for the period of 1982-2022 — the period over which the satellite data used are available. These temperatures are 3.89°F above the long-term (1982-2011) Summer average of 58.25°F.

Weekly Temperatures

In the below table, we highlight how the SST for each week this summer compares to a 30-year baseline period (climatological averages from 1982 through 2011).

The observed SST, long-term average SST, and SST anomalies (departures from the long-term average SST) are shown. As expected, SSTs generally rise as the summer season progresses, with anomalies showing no clear trend over the course of the season. Rather, departures from the long-term average hovered around 3°F above normal with a few weeks punctuated by anomalies exceeded 5°F.

Observed, climatological average, and deviation from the climatological average (i.e., temperature anomaly) for SST at a weekly resolution in the Gulf of Maine during summer 2022 (defined as June 1st - August 31st)
Weekly Sea Surface Temperatures - Summer
Summer (June 1st - August 31st)
One-Week Period Observed Temperature Climatological Average Temperature Anomaly
°F °C °F °C °F °C
Jun 01 - Jun 04 53.5 12.0 49.6 9.78 3.92 2.18
Jun 05 - Jun 11 55.5 13.1 50.9 10.50 4.61 2.56
Jun 12 - Jun 18 57.4 14.1 52.7 11.50 4.78 2.66
Jun 19 - Jun 25 56.6 13.7 54.4 12.50 2.21 1.23
Jun 26 - Jul 02 59.3 15.1 56.2 13.40 3.09 1.72
Jul 03 - Jul 09 61.2 16.2 57.8 14.30 3.43 1.90
Jul 10 - Jul 16 62.6 17.0 59.2 15.10 3.38 1.88
Jul 17 - Jul 23 63.6 17.6 60.3 15.70 3.26 1.81
Jul 24 - Jul 30 64.8 18.2 61.3 16.30 3.47 1.93
Jul 31 - Aug 06 66.5 19.2 62.0 16.70 4.53 2.52
Aug 07 - Aug 13 67.7 19.8 62.4 16.90 5.27 2.93
Aug 14 - Aug 20 65.7 18.7 62.5 16.90 3.23 1.79
Aug 21 - Aug 27 66.9 19.4 62.2 16.80 4.66 2.59
Aug 28 - Aug 31 67.0 19.5 61.9 16.60 5.17 2.87
Data Source: NOAA OISSTv2 Daily Sea Surface Temperature Data.
Climatology Reference Period: 1982-2011.

Monthly Statistics

Looking at monthly averages (as opposed to week-by-week conditions), we see each month was 3.36°F or more above the 1982-2011 climatological average. August showed the largest deviation from the long-term climatological average, with an average SST anomaly of 4.55°F.

Month Observed Temperature Climatological Average Temperature Anomaly Temperature Progression
°F °C °F °C °F °C High/Low °F
Jun 56.5 13.6 52.8 11.6 3.75 2.08
Jul 62.9 17.2 59.5 15.3 3.36 1.87
Aug 66.8 19.3 62.2 16.8 4.55 2.53
Data Source: NOAA OISSTv2 Daily Sea Surface Temperature Data.
Climatology Reference Period: 1982-2011.

How Does 2022 Compare?

2022 is among the warmest summers seen in the Gulf of Maine during this 41 year period. When compared against all previous summers for which we have reliable satellite data (i.e., back to 1982), this year ranks 3rd among the hottest on record. The top 5 warmest Summer have all occurred in the last decade.

Marine Heatwave Timeline

The most commonly used definition of a “marine heatwave” (MHW) is when daily average SST’s exceed the 90th percentile of a climatological (i.e., 30-year) average for at least 5 consecutive days. Successive heatwave gaps of 2 days or less are considered part of the same event.

Using this broadly accepted definition, the Gulf of Maine has experienced MHW conditions for 0.95 of summer 2022 A brief reprieve in mid-May lasted less than two days, so it did not constitute a break in the heatwave event.

Heatwave Anomaly Timeline

Presenting SST conditions in terms of anomalies (figure below) as opposed to absolute values (figure above) illustrates in greater detail the magnitude of MHW conditions throughout the summer.

The most extreme anomalies this summer occurred in August, with temperatures exceeding \(6°\)F above the climatological average.

Heatmap of Temperature Anomalies and Heatwave Events

Looking at the full record of daily SST anomalies in the Gulf of Maine (figure below), the distinct thermal regime shift beginning around 2010 is evident. Indeed, since 2012, the Gulf of Maine has experienced far more persistent MHW conditions (indicated by solid black lines) than at any other point in the satellite record.

Monthly Rankings Heatmap

Longest Heatwave on Record

This summer marked the conclusion of the Gulf of Maine’s longest heatwave event.

This event spanned from 2021-01-01 to 2022-06-19 - ultimately lasting 535 days. During that period temperatures were on average 3.87°F above temperatures observed during the 1982-2011 climate reference period.

Spatial Distribution of Seasonal Anomalies

From a spatial perspective, the Gulf of Maine and surrounding areas experienced above average SST’s for much of the region during summer 2022, but with particularly warm patches to the south and east of Georges Bank. The highest seasonally averaged anomaly of any location above was 6.73°F.

Monthly Temperature Anomalies

Average monthly temperature anomalies are displayed below. The warmest anomalies were concentrated just south of the domain studied in this analysis in June, by July SST anomalies within the Gulf of Maine were equally hot. Monthly-averaged SST anomalies in the Gulf of Maine and the surrounding areas reached > 8°F warmer than during our climate reference period (1982-2011).

 

A work by Adam A. Kemberling

Akemberling@gmri.org